What Malware Does

Not all computer viruses are designed to be destructive. They all do, however, use various resources that could be put to other uses by a computer so in that regard, all computer viruses and other malware have some effect on a computer.


I think computer viruses should count as life. I think it says something about human nature that the only form of life we have created so far is purely destructive. We’ve created life in our own image.

Stephen HawkingWeb Link

Despite Hawking’s quote, not all computer viruses are designed to be destructive. They all do, however, use various resources that could be put to other uses by a computer so in that regard, all computer viruses and other malware have some effect on a computer. Those that are programmed to have an effect, however, do so in a wide variety of ways that can be subtle or very destructive.

Among the subtle effects are various screen display changes. Early viruses tended to uses these sorts of effects to call attention to themselves when the author wanted that to happen. For example, random icons might be displayed on the desktop (e.g., the Windows 95 virus MarburgWeb Link. Or, in the extreme, the virus might even want you to play a game (e.g., PlaygameWeb Link).

Not all viruses are so benign however. There are many that will attempt to be very destructive to data. Some (e.g., MichelangeloWeb Link) attempt to overwrite the data on your computer. Others (e.g., Hungarian Filler) just overwrite the file allocation table or directory. Still others (e.g., Disk KillerWeb Link) may attempt to encrypt your data and then hold you hostage by offering the decryption key for a fee. There is little limit to the imagination of the people who write these beasts and so just about anything is fair game.

I’ll get an argument on this but there are even viruses that attack the computer’s hardware. Many say you can’t destroy computer hardware with malware but Computer Knowledge contends that rendering the hardware unusable is as good as destroying it and it’s in this regard that malware can attack hardware. In particular, today, the BIOS in a computer (the small program on a chip that is called when a computer starts up) usually comes on a chip that can be rewritten using software in order to provide the rare update to the BIOS without requiring the user to change the hardware chips to perform the upgrade. Such BIOS chips can be easily overwritten or cleared and that renders the computer useless until and unless you can use a low-level utility on removable media to restore the BIOS and allow the computer to then boot normally. While this damage is not permanent, it is very inconvenient and not everyone will be capable of doing this sort of restore. An example of this sort of virus is the CIH Spacefiller virus.

Most today, however, are not attempting to destroy data but, instead, are after some sort of profit. Virus writing has turned a commercial corner and money can often be the driving force behind the various payloads. Here are some more specific actions that malware can take. Keep in mind that this is not an exclusive list.

Child porn storage can also be a product of virus activity. It’s a nasty world out there.

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